While many attempts over the past years have been made to correct surgically the vision defects detected by refractive examination instead of corrective glasses or contact lenses, it is only since the work of Dr. Sato of Japan was refined by Dr. Fydenoy of Russia that numbers of researchers and doctors in the field have resorted to surgical techniques with some degree of permanent success one promising procedure is defined as "manual radial keratotometry" wherein a plurality of deep radial cuts are made in the cornea of an eye which refraction has shown to be myopic to allow internal eyepressure to alter the corneal curvature to correct the visual defect the cornea heals quickly compared to other types of tissue, and the scar tissue from the surgery does not interfere with later sight and is not obvious to an observer farther from the eye than two feet while there is some danger of infection, as from any surgical procedure, and differing periods for healing, freedom from the need to wear corrective glasses or contact lenses is of greater value to persons in certain professions, and has important psychological advantages for other persons.
One problem with manual keratotometry in the past has been the control of the depth of the incision, since too deep a cut may damage the endothelium layer of the corneal inner surface and the blade penetrates the Descemet membrane into the anterior chamber of the eye. The endothelium is essential to the general health of the eye and cell loss is permanent. On the other hand, if the incision is shallow, the correction may not be permanent. Since the thickness of the cornea increases from the central optic zone to the circle of the limbus, the edge of the cornea, it is not possible to merely carefully set the extension of the cutting point from the guard or shoulder of the special scalpel to limit penetration. While pachometry procedures can accurately guage the thickness and profile curvature of the cornea there are few practitioners capable of translating such parameters into manual controls to effect radial or chordal incisions of sufficient exactness as to accomplish the precise correction dictated by the refractive, pachometric and keratometric measurements.
Therefore the method and apparatus of the invention are purposed to overcome the possible imprecision of purely manual keratotometry and to provide a method and apparatus aiding the surgeon to operate simply and with precision, minimizing danger to the eye and to the success of the procedure. The operation is one capable of being performed in properly equipped doctor's offices and outpatient clinics under topical anesthetic with anesthesia standby.